A certain number of proposals are known in this field, such as those in documents EP 0878332, EP 1630026, WO 2006/032669, US 2007/0257570, WO 2007/083209 or WO 2009/124892.
In the present application, the expression “motorized hub” is used to denote the mechanical assembly comprising the hub, the hub carrier, steering of the hub relative to the hub carrier, the electric power system and the hub braking means. The motorized hub is therefore intended on the one hand to receive a wheel equipped for example with a tire and on the other hand to carry a vehicle, generally through the intermediary of suspension means. In the present application, the expression “motorized wheel” is likewise used to denote the mechanical assembly comprising the motorized hub defined above and the corresponding wheel.
One of the difficulties in adopting such motorized hubs for mass-produced vehicles is compatibility with the solutions already adopted and approved by the constructors for certain elements such as suspension systems and wheels. Another difficulty is that of achieving a simple, compact system which is as light as possible, so as to make the cost acceptable to said industry.
In particular, the incorporation of electric motors inside wheels is particularly desirable because the adoption of electric drive systems frequently involves the need for on-board batteries for storing electrical energy which, even with the highest-performance technologies known to date, requires a sufficient volume to be dedicated to the batteries on board the vehicle, the autonomy of the electric vehicle otherwise being highly reduced. A similar reasoning can be made in the case of fuel cell or hybrid parallel vehicles.
Furthermore, if it is wished to be able to develop sufficient drive torque, it is necessary to install reduction means, because it is not possible, with a sufficiently compact electric motor, to develop sufficient torque to directly ensure drive of a passenger vehicle.
Furthermore, parallel hybrid vehicles whose internal combustion engine generally allows travel at relatively high speeds (for example 150 km/h) constitute a particular problem in terms of choice of electric drive reduction ratio.
Finally, it is generally necessary to incorporate in the wheel not only the electric motor, and the associated necessary reduction means, but also a mechanical braking device (disk brake or friction drum).